Type hammer actuating means in high-speed printers



Sept. 9, 1969 BELSQN' ET AL TYPE HAMMER ACTUATING' MEANS IN HIGH-SPEED PRINTERS Filed Jan. 1968 5 Sheets-Sheet l INVENTORS ROSS A. BELSON BICKOFF CHARLES ATTORNEY Sept 1969 R. A. BELSON E AL TYPE HAMMER ACTUATING MEANS IN HIGH-SPEED PRINTERS 5 Sheets-Sheet P.

Filed Jan. 2, 1968 INVENTORS ROSS A. BELSON CHARLES BICKOFF FIG.4

ATTORNEY Sept. 9, 1969 R, BELSON ET AL TYPE HAMMER ACTUATING MEANS IN HIGH-SPEED PRINTERS Filed Jan. 2. 1968 3 Sheets-Sheet 3 FIG. 7

INVENTORS. R085 A. BELSON BY CHARLES BICKOFF ATTORNEY United States Patent 3,465,670 TYPE HAMMER ACTUATING MEANS IN HIGH-SPEED PRINTERS Ross A. Belson, Natick, and Charles Bickofi, Quincy,

Mass., assignors to Honeywell Inc., Minneapolis, Minn.,

a corporation of Delaware Filed Jan. 2, 1968, Ser. No. 695,186 Int. Cl. B41j 9/10 US. Cl. 101-93 8 Claims ABSTRACT OF THE DISCLOSURE A simplified high-speed printer using a continuously rotating type roll swept past an array of aligned print hammer slugs, the roll being selectively impacted by each slug when an associated (one of a set of) hammer actuator is fired, the printer being characterized by the actuators, each being shared by an associated set of slugs all driven in common thereby, all but one of these sharing slugs, in a set, being disabled at any given phase (character-period) of each print-cycle corresponding slugs in each set having a respective ON period in every cycle. That is, in a typical embodiment with a conventional full complement of print slugs, each independently mounted to correspond with a respective print position (column), adjacent pairs of slugs are arranged to be activated by a common, selectively-fired solenoid actuator, each such actuator, being arranged to print-thrust both associated slugs, except that only one slug is enabled during each alternate print-cycle, other slug being contemporaneously disabled and out of actuator-contact; and this disablement being synchronized with type roll rotation, preferably by a system of opposed pairs of cam-lobes rotated by a common shaft to alternately cock one or the other slug (in each pair) forward, out of actuator range.

PROBLEMS, FEATURES OF INVENTION In the art of providing printer mechanisms for computer print-out and the like, a common practice is to supply a full set of print-hammer slugs, i.e. one for each print-position (or print-column) along a print-line, together with a full complementary set of actuators (or print-hammers, customarily solenoid-operated), one for selectively driving each respective slug. Preferably, each slug is mounted for free flight travel and, thus, independent of its actuator. However, due to the long-standing difficulty of crowding these impacting mechanisms as closely as customary print-spacing requires, some serious problems are presented; e.g. interference from adjacent slugs (or from adjacent magnets), the high cost of producing a full set of 132 hammer/ actuator parts in compact miniaturized form, etc.

Some solutions come to mind. For instance, one may elongate (actuator) hammer faces to span a number of print-columns and/or one may oscillate a staggered set of single-column hammers, back and forth between respective slugs (across a multi-column span for each hammer), or the like. Such approaches may involve reducing the complement of form-impacting elements (such as the print-slugs aforementioned) and, compensatorily, arranging the element array to laterally-reciprocate as a unit. One example would be a ponderous array of actuatorhammers arranged to oscillate between print-positions. But such an array is too massive to be practical for reciprocation at the required printing rate. Another example would be shifting a set of (slug-like) form-impacting elements, so that each periodically registers with one in a set of associated print-columns. A salient disadvantage of this approach is the high risk of lateral smearing of 3,465,670 Patented Sept. 9, 1969 printed characters because of the difiiculty in securing (and maintaining) proper column registration of the impact elements when they are shifted laterally at the high accelerations necessary for high-speed printing. There are other disadvantages to this approach also. The present invention provides a new solution to these problems without need for laterally shifting form-impacting elements (e.g. slugs) and with no need to laterally shift an array of actuation elements either; instead, providing a full complement of relatively standard, free-flight, print slugs and associated shared, multi-slug, actuators together with novel select means for periodically disabling all but one slug in each actuator-sharing set.

The foregoing difiiculties have been faced, and moreover, a simplification of simplifying print-hammer structure has been elfected as well, by providing a modified (e.g. staggered) arrangement of font on a print roll together with slug-select means and multi-column spanning actuator means. By such an arrangement, a row of font is print-registered piecemeal, i.e. presented to successive groups of print-columns in waves; each wave corresponding to a group of ON columns (i.e. having their slugs enabled simultaneouslyin two waves, one for every odd column, then one for every even column). A similar checkerboard font array has been proposed before but has been of such a type as to introduce serious drawbacks, such as requiring major changes in the size and font-arrangement on the print roll (workers in the art well know that a larger roll is usually quite undesirable and involves increased costs). The invention provides a solution to these problems without requiring any such changes in a print roll.

Thus, it is an object of the invention to solve the aforementioned problems and provide the aforementioned features and advantages. Particularly, it is an object to provide a high-speed printer wherein hammer actuate means are conserved by sharing multi-slug actuators with a full complement of independently-mounted slugs. Another object is to provide a simplified hammer actuation arrangement. Still another object is to so provide without necessitating any radical departures from a standard type roll design. Still another object is to provide such a sharing arrangement without requiring a special type roll, such as one having a staggered font, if this is not desired.

Still another object is to provide a sharing arrangement including select means for cyclically enabling successive impact elements in a group for impact coupling with an associated shared common actuator. A more particular object is to provide such select means in a printer exhibiting a full, normal complement of slugs (e.g. one for every print position), the slugs being arranged in groups, each with a common (spanning) actuator means. An even more particular object is to arrange such select means and actuator means so as to disable all nonselected slugs in a group, such as with a multi-lobe camshaft, with a shuttled cocking bar, or like means, for throwing non-selected slugs out of reach of actuator elements. A related and alternative object is to arrange such select means to stop-limit all such non-selected slugs, such as through resilient damping pads on a shuttled stop-bar. Another, more general object is to arrange such high-speed printers to include slug/actuator coupling means selectively operable to periodically effect such coupling at prescribed select times. I

The foregoing objects and features of novelty which characterize the invention, as well as others which will occur to those skilled in the art, are pointed out with particularity in the appended claims forming a part of the present specification. For a better understanding of the invention, its advantages and specific objects attained with its use, reference should be had to the following description of preferred embodiments, including the accompanying drawings.

According to one such embodiment, the invention provides a relatively conventional high-speed printer including a standard type roll (with conventional dimensions and font-arrangement) and a full conventional array of free-flying print slugs, one for each print-position; this printer being characterized by adjacent pairs of slugs being arranged to be driven by a common actuator and by a system of select cams adapted to periodically, and alternately, disable each slug in a pair, alternately cocking-it-forward out of actuator reach, disabling it for a respective portion of every print cycle, this select-cam system being synchronized with the type roll (and with related print signal means) so that each slug will be printably" coupled with its associated actuator at a select time which corresponds to the passage of each font row at its respective print column.

In the drawings wherein like reference characters denote like parts:

FIGURE 1 is a very schematic, partly fragmented, isometric showing of part of a high-speed printer test apparatus incorporating a time-shared actuator arrangement according to one embodiment of the invention;

FIGURE 2 is an enlarged elevational view of a representative number of the print slugs of the embodiment in FIGURE 1, high lighting associated actuating and select means;

FIGURE 3 is a highly schematic isometric showing of a pair of print slugs like those in FIGURES l and 2, together with common, associated select cam means and solenoidal actuator; FIGURE 3A being a schematic side view of the elements in FIGURE 3 sectioned through one print slug;

FIGURE 4 is a plan view of two pairs of slugs in a modified alternate embodiment including an actuating arrangement functionally similar to that of FIGURE 3, but modified somewhat to include a different select means; FIGURE 4A being a side sectional view thereof taken along lines IVIV;

FIGURE 5 is a very schematic isometric showing of another modified alternate embodiment including a pair of slugs in an actuating arrangement functionally similar to those in FIGURES 1-3 and 4, but employing a different slug-select means; FIGURE 5A being a side elevation of one slug in disabled condition;

FIGURE 6 is a very schematic isometric, fragmentary showing of another modified alternate embodiment including two pairs of related print-slugs (phantom) associated common actuators and select means in an arrangement functionally similar to the foregoing, however with the select means modified; FIGURE 6A being a simplified plan view thereof, as viewed from the location of the slugs (phantom);

FIGURE 7 is an idealized fragmentary plan view of another modified embodiment, after the manner of FIG- URE 4; and

FIGURE 8 is a schematic view of still another embodiment of print slugs and actuating means therefor.

ONE EMBODIMENT FIGURE 1 shows some exemplary details of a printer arrangement on a test stand, this being understood by those skilled in the art to be only schematically indicated but representing any conventional high-speed printer. This arrangement includes a conventional type roll PR mounted to be continuously rotated (by means not shown) between a pair of frame members F, F spaced by a support bar B, together with a form-guiding roll R adapted (conventional tractors and associated guide means are understood, though not shown) to present a conventional paper form (web W shown in phantom) in print-able relation with type roll PR (and ribbon, not shown) along a printing plane PP, roughly tangent with roll PR and web W to be intersected by the path of 4 (actuated) print-slugs (cf. FIGURES 3, 3A), at respective print-column locations.

Referring also to FIGURE 2, those skilled in the art will appreciate that a print hammer arrangement is provided which, generally speaking, comprises an array of aligned print slugs T, each one registered with each print column location and presenting its tail portion (t etc.) in operative, driven (reciprocable) relation with associated actuator heads H (on actuator block HB) somewhat conventionally. However, according to one feature, each head (e.g. H is provided with an elongated face spanning an associated pair of slugs (e.g. slugs t t spanned operatively by H for thrusting both into printing relation with type roll PR (through print plane PP) in a manner known in the art. Each actuator head H preferably comprises a solenoid-actuated, pivoted lever, arrangement of otherwise known construction, being mounted from hammer block HB to be normally held damped against an associated adjustable stop ST by an associated engaged intermediate portion of a resilient damping pad P. Each actuator head may be adjusted into a prescribed rest position (with its face along hammer rest plane PL-3) by the associated adjustable screw stop (e.g. stop ST for hammer H The structure and operation of such hammer arrangements is well known, being also indicated in FIGURES 3, 3A and (except for the relation of the hammer head with associated print slugs) will not be further discussed, since virtually any analogous selectable drive means may be used as known in the art.

According to the invention, an array C of select (or enabling) means is also provided to determine the driven relation of each slug 2 with its associated actuator head H. In the embodiment of FIGURES 1-3, this select means takes the form of opposed adjacent pairs of like camlobes (c c c etc.) affixed on'a continually-rotated (by means not shown) camshaft CS to be, each, periodically rotated into disabling relation with a respective slug, camming it forward. The lobes in each cam pair are opposed and operatively associated with a respective slug (e.g. lobes c c with slugs t t respectively). As FIGURES 3, 3A indicate each lobe is offset on shaft CS with respect to its paired mate so that the lobe-pair may disablingly advance one slug in the associated pair at alternate times (e.g. slug 1 at print-position #2 is shown cocked forward, out of actuator reach and disabled; where its mate, slug f is not, being enabled-FIGURE 2). According to this feature, this cocking moves the thus-disabled slug part-way towards plane PP, out of rest position so that its tail and head (ends) register along tail-offset plane AD-AD; and head-offset plane PL-2 PL-Z, out of the launch-path of the associated actuator head; this being synchronized during alternate halves of each rotational cycle of shaft CS. The foremost position of the hammers H may be understood as controlled (e.g. to traverse hammer excursion G", just short of tail-offset plane AD-AD, FIGURES 2 and 4), and stop-limited so as to avoid impacting a disabled slug. That is, the tail of a slug so cocked is assumed advanced effectively beyond G" in its inactive mode to present its head along head-offset plane PL-2 PL-2 (as with cocked slugs t t I in FIGURE 2). Cocking-plane PL-2 is thus intermediate the printing plane PP and the normal plane (head-rest plane PL-1 PL1, the locus of heads of enabled slugs, e.g. t t t in FIGURE 2). Thus, every second slug in illustrative array T is alternatingly enabled (active and at rest) and then disabled (inactive and offset).

Thus, those skilled in the are will understand that camshaft CS is to be rotated in synchronism with type roll PR so that one slug in each pair will be disabled each half-cycle; the slugs in each pair being oscillated, opposingly, between active and inactive conditions during alternate character periods, i.e. the period corresponding to the passage of all font rows for a given character on type roll PR. For instance, according to one embodiment of the invention, type roll PR presents a complete alpha-numeric font past print plane PP during each half-rotational cycle (each 180), in which case shaft CS will be made to rotate synchronously so as to disable one slug in each pair (like t t t in FIGURE 2) during one such half-rotation, leaving enabled the other slugs (like t t t then reversing this during the next half-rotation. Thus, one feature of the invention will become apparent to those skilled in the art whereby slug-actuator means (such as hammer H may be time-shared (i.e. used to alternately drive) by a pair of print slugs (e.g. t t the slugs being controllably disabled by select means with obvious attendant efliciencies and advantages. Of course, in such an arrangement, with only half the slugs enabled at any one time, some printing speed will be sacrificed (i.e. falling below a prescribed maximum speed, given a certain operating mode for type roll PR). Thus, at the start of a lineprinting period, one-half of the offsetting cams (c etc.) may be understood as in disable condition (thus, an alternate, one-half of the slugs are disabled; the other half enabled); to remain so while a first sub-scan occurs. There will be two such sub-scans per line, memory being accessed for print commands therewhile, and actuate-magnets being enabled while a complete set of character-rows on roll PR is being presented (e.g. characters 140 and A through Z presented at all columns during one half-revolution of PR), printing therewhile being effected only at these alternate positions (columns). After this first sub-scan (e.g. after printing is completed in the odd columns this being signalled by known means), a second, similar sub-scan is effected for the other (e.g. even columns) print positions; the same actuators and related control circuitry etc. being re-employed for this. The speed of print-roll rotation, solenoid-recovery time, etc. will thus govern the timing of such scanning, for instance, setting a speed limit on them.

The construction and operation of the elements in FIGURES 1 and 2 will be better understood upon consideration of the very schematic operational showing of a propaedeutic pair of slugs (t 1 in FIGURES 3 and 3A. Here, it may be assumed that slugs t t are like those in FIGURES 1 and 2, being pivotably mounted quite conventionally, such as from a fixed common base B (see also FIGURE 5) to be independently, flexibly pivoted, such as by mounting conventionally on flexure pivots f etc. as known in the art. According to the invention, each slug in such a pair is enabled for print impacting at alternate times, i.e. at alternate half-cycles in the rotation of camshaft CS (this corresponding to a disabling engagement of one of the cam-lobe pairs 0 c with a respective slug t t at an ear portion thereof, a :1 respectively). That is, as will be apparent, each slug has an associated raised (ear) portion u (e.g. M 14 respectively for t 1 this ear being adapted to be engaged and offset, in cam-follower fashion, by an associated cam lobe (e.g. c 0 respectively for a a during part of the rotational cycle thereof on shaft CS. This engagement will, as stated, so offset (advance) the slug, beyond the (foremost) excursion of the associated hammer H as to be disabled during alternate off cycles. Note that a cut-out (or channel g) is understood as provided in each slug to form cars it (e.g. g for c and accommodate the respective pair of cam lobes so that only ears u will be so engaged, this cut-out being sufiicient to clear other slug surfaces. For example, lobe 0 is shown in FIGURES 3, 3A as engaged against ear u (i.e. non-selected or disabling condition) so as to, now, thrust slug t disablingly-forward, advancing its head from plane PL-1 to plane PL-2. Elements t u c and CS are understood as shown sectionally in FIGURE 3A with the companion slug unit in enabled (ON) position, i.e. with associated cam lobe c rotating free in associated slot g in slug t this slug being in normal position with its head along plane PL1 and its tail along plane PL-3 in driveable relation adjacent the thrusting face hf of associated actuator head H (to be driven as indicated by arrow AH).

Of course, slugs 1 may also be spring biased in one, or both, actuation directions (not shown, but often done conventionally) or may be otherwise modified over this embodiment while still embodying the aforedescribed shared-actuator feature. For instance, three or more slugs may be arranged to share an actuator; the type roll format and the selecting/actuation-control means (e.g. logic) etc. being modified accordingly. Furthermore, it will be recognized that this feature will be useful for differently mounted arrays of free-flying slugs) e.g. those dispensing with flexure pivots etc. and otherwise maintaining the slugs properly aligned, guided during actuation; and other arrangements discussed below. Using this feature in high-speed printers analogous to the above embodiment (FIGURES 1-3), good results have been achieved. For example, using a relatively standard print roll (e.g. 46 contiguous characters, rotating at about 800 rpm), good quality printing has been derived at speeds of from 400600 l.p.m. (lines/min). Of course, in any event, such actuator sharing will necessarily reduce print speeds somewhat (e.g. typically about one-half or less), and this must be borne in mind in assessing where to use it to advantage (e.g. for medium speed printing or slower).

MODIFICATION A modified embodiment, shown in plan view in FIG- URE 4, may shed more light on the invention as well as indicating a modified mode of actuator sharing. Here the printing elements may be understood as like the foregoing except where specified. Thus, print roll PR may be assumed to be continually swept past print plane PP, having a relatively conventional array of font thereon, such as exemplary font-characters A, aligned along row aa to register With respective print positions (columns) I, I, II, II and font-characters B similarly aligned along row bb. Positions I, I, II, 11' etc. will be understood as corresponding with print-columns where respective print slugs S S S 8., etc. intersect print plane P and impact the paper, as is conventional in the art. Also, and like the preceding embodiment, double-column actuators (e.g. A A indicated representatively), each in driving relation (like hammers H above) with an associated pair of these print slugs S (e.g. A with S S A with S 8,). Each so-associated pair of print slugs S will include a raised ear portion 2 like ears u above), adapted to provide a thrust-surface (cam-follower) for cyclic-advancement by the select means to be disabled, i.e. by a forward portion of a select-bar SB (cf. FIGURE 4A also). Each ear E will be understood as cammed forward by the associated part of select-bar SB at periodic disable times. That is, a selected slug (e.g. S or S shown) will remain uncooked and spaced a prescribed normal gap G from print-plane P and thus left impactable by the associated actuator A (e.g. A for S during its driving excursion G" (see FIGURE 3A also). Conversely, and as before, a disabled slug (such as S or 8,) is intended to be cocked-forward closer to print plane P (cf. offset gap G') at non-select times so as to be, then, effectively beyond the thrust (G) of its actuator.

As in the foregoing cases, each slug in a pan is intended to be alternately cocked-forward (disabled) by the select means SB; however, SB in this case will be understood .as modified to comprise a bar which is shuttled (that is, oscillated back and forth laterally as indicated by the arrowby means not shown but conventionally provided) in prescribed synchronism with print roll PR (as with select shaft CS aforementioned). One side of bar SB is therefore adapted to cockingly engage alternate (non-selected) ears e (in each pair at alternate times), while prescribed cut-outs (notches) are provided to clear the companion, selected ear leaving the selected slug uncocked and enabled. Of course, beveled camming surfaces may be understood as conventionally provided on the engaging portions of ears 2 and along the sides of notches n (e.g. notch n for slugs S S so as to smoothly and gradually engage these in cocking the slug forward and returning it, while bar SB is shuttling back and forth to thus disable every other slug alternatingly. Here, and in the foregoing embodiment, shuttle drive means, return spring means, etc. will be understood as provided conventionally though they are not shown.

OTHER MODIFICATIONS Workers in the art will appreciate from the foregoing that the above aspects of the invention specifically teach actuator-sharing by a cocking-forward mode, i.e. cocking print slugs forward, out of impact-alignment with an associated shared actuator, to disable them periodically. However, it will be understood that while rotating camshaft means and shuttling bar means are disclosed as preferred methods for implementing this, other analogous means will come to mind. For instance, where solenoid hammer actuators are indicated, other equivalent devices may sharingly drive the driven elements. Also, where print-slugs were indicated as driven elements, other analogous sets of elements may be so driven in sharing groups. Further, while various select means were indicated for periodic forward-cocking of the driven elements other like means will come to mind. For instance, although no significant wear problem was observed between cocking lobes (like c etc. vs. n etc.), if this were feared, conventional modifications could be implemented such as changes in materials (for lower wear, less friction, etc.) and of structure (e.g. rollers on one or both sliding surfaces, etc.). Further, while this periodic, synchronous misalignment of alternate slugs (out of driven relation with the common actuator) has been indicated above as a forward-cocking mode of misalignment, it will be appreciated by those skilled in the art that other, different modes of misalignment may, in certain cases, produce the same result, such as by a sidewise cooking of a slug (without interfering with its neighbor), as is indicated, in a very idealized manner, in FIGURE 7.

It will be understood that the arrangement in FIGURE 7 is like the foregoing except for effecting a lateral cocking (left or right out of actuate-path), typically requiring minor modifications in the slug arrangement (without disturbing the close, critical inter-slug spacing) as well as in its relationship to the actuators etc. to accommodate means (cam means or the like) to selectively throw alternate slugs sidewise. Such means will displace a slug, somewhat out of the normal actuator-printcolumn registration axis (e.g. in FIGURE 7 slugs iS 1'8 along respective column-axes I, II to common actuator face iA). Thus, in FIGURE 7, an exemplary pair of slugs 1'8 1'5 (indicated as in enabled and disabled conditions respectively; with their converse condition in phantom) are indicated to be operatively associated with a common shared actuator iA so the latter can thrust an enabled one (18 indicated) thereof along its printpath (column I) and not drive the other (iS so indicated, not to be driven along II). Workers in the art will recognize that side-thrusting cam means can be provided (by known means not illustrated here) analogous to cam lobes C in FIGURES 1-3) to cock each slug laterally to these indicated positions. Such a select means is here schematically represented by a shuttled select-bar [SB adapted to alternately pull one slug (in each pair, e.g. iS to one side, disablingly, and then push the companion slug the other waywithout, of course, interfering with other adjacent slugs therewhile.

To minimize the necessary cocking-excursion impact means may be provided on the slugs (such as the projections shown on is, and 18 which leave the slug unactuated when it is shifted out of the path of actuator face iA. Of course, care should also be taken to nonetheless maintain lateral column-registry during printing, such as with guides iGd. However, the preferable cocking mode definitely appears to be along the printing-path direction (e.g. forward per FIGURES l3 or 4), partly because this subjects the slug mounting only to stresses along the intended (printing) direction, without skewing it with respect thereto and without introducing the problem of providing off-axis compliance (in disable condition) together with on-line alignment (during enable condition, printing thrusts).

FIGURES 6 and 6A illustrate, very schematically, another technique for employing common actuators and a shuttling select means with free-flying print-slugs. Here, a modified actuator unit, 6U, is (fragmentarily) illustrated wherein the shuttled select bar SB-S is adapted to selectively make" contact between one or the other slug (in each pair) and a common actuator. Unit 6U is essentially the same as the other described embodiments (e.g. see FIGURE 4 or FIGURE 5) except as here specified. Unit 6U will be understood as including an array of slug pairs (e.g. HH and HH HH and HH,, etc.indicated in phantom) and an associated array of actuators (e.g. actuator heads A and A for I-II-h-HH and HH HH respectively) like those aforementioned except that select bar SBS is arranged to be selectively interpositioned therebetween. That is, bar SB-S includes a set of striker fingers (if), these being so arranged and shuttled (by means not shown) on SB-S as to present each finger between one of an associated pair of slugs (tails thereof e.g. finger if-12 for slugs HH and HH and their common actuator (e.g. AA-12 for HH and AA12) so as to be actuator-driven and, in turn, drive this slug printingly. Fingers if will thus be understood as somewhat compliant along this (small) driven direction (e.g. comprising a flexure mounted or like printed array, not shown but well known). Thus, during one half-cycle bar SBS will present fingers if to enable half the slugs (e.g. as shown, fingers if-12, if-34, if56 disposed to drive slugs HH HH and HH respectively); while during the next half-cycle, bar SBS will be shuttled to present these fingers to enable the other slugs (e.g. HH HH HH Unlike the foregoing select means, this means periodically enables slugs in its group (vs. disabling them).

FIGURES 5, 5A illustrate an arrangement like the foregoing except for select modifications hereafter described and involving an alternative stop-bar type select means including means for damping the driven energy of nonselected slugs (rather than de-coupling means). Thus, FIGURE 5 shows an exemplary pair of print slugs HH HH operatively associated with a common, doublewidth actuator AA-l, generally adapted to be selectively impacted (arrow) against slugs HH to drive them printingly (against an associated type wheel, not shown, but indicated by print-plane PP outlined in phantom and in the side view in FIGURE 5A). This arrangement may be understood as like the foregoing embodiments except where indicated, e.g. including an array of free-flying slug pairs. According to one feature of this embodiment, illustrating another mode of actuator-sharing, each slugpair is enabled for driving by a stop type select means, such as the illustrated shuttling stop bar SB". This disabling action is functionally similar to the aforedescribed cocking disablement mode, but operates rather as selectively applied energy-absorber (stop) means. Bar SB" is thus functionally rather similar to select bar SB in FIG- URE 4, being similarly constructed and operated, except as here specified; however, including detent (or stop) fingers ft ft etc. Fingers ft are each registrable with a slug-ear portion ee projected from an associated slug HH and configured to engage It (eg. being about the same width). Detents fr are separated by notches sufficiently wide to clear an ear ee when not registered over it and thereby allow the passage of an enabled slug when the latter is launched by its actuator (e.g. when actuator AA-1 launches slug HH in FIGURE 5; also FIGURE 5A in phantom).

Thus, unlike bar SB, bar SB" is intended to function as a set of selective, reciprocating stops which are shuttled in prescribed synchronism (with the font passage) so that detents ft engage alternately cover a nonselected one of an associated pair of ears ee disablingly. In this arrangement, it may be understood that such a detent intercepts one of its respective slugs after both are hit by the common actuator, preventing printing-impact since the driven energy of that slug is absorbed such that it will not reach print-plane PP. For this purpose, resilient absorbing pads pd are preferably provided on the lower, ear-confronting, surface of each detent ft. Thus, for instance, after the striking face hf of actuator AA-l has been (synchronously) actuated to be thrust for-ward (from rest-plane PL-A3) a prescribed actuator excursion (to be arrested at forward-plane AAD, cf. arrow), it will strike both associated slugs HH HH so that both fly forward from their rest position (e.g. nose-rest plane PLA1), in free-flight for a time such that one slug (disabled slug HH shown engaged against pad pal-12), having flown beyond actuator-limit plane AA-D a prescribed amount G-A and penetrated somewhat into this pad, will be arrested short of a full print-flight (i.e. ear stopped at plane PH with nose at nose-stop plane PL- A2, short of print plane PP) and be urged (e.g. by other return means, not shown) back to rest position. The arrows on elements AA-l and HH suggest this stopreversal while the phantom indication of HH shows a full, unstopped printing flight, beyond PP.

Thus, it will be recognized that, whereas the slug-disabling (select) means in the preceding embodiments acted to misalign alternate print slugs (within a group), this embodiment teaches a different select means achieving somewhat equivalent results by a selectively stopping (damping) of disabled slugs to prevent them from print-impacting the type roll. Those skilled in the art will visualize other equivalent stop means that may also be used for this purpose.

Those skilled in the art will recognize that, where the foregoing embodiments provided select means which periodically enabled or disabled successive print slugs in a group (or effectively disable them by intercepting them) there are other, differently-operating, equivalent select, means which may achieve the same results. For instance, referring to the foregoing embodiment in FIGURES 1-3, the offsetting cam lobes may enable a contacted slug (vs. disabling it), e.g. by thrusting it into, not out of, actuation path, etc.; such as with the alternate embodiment (unit 8a) schematically and exemplarily indicated in FIGURE 8. That is, unit 814 will be understood as like the embodiments of FIGURES 1-3 (e.g. cf. FIGURE 3A) except where indicated, comprising a set of slugs (representative slug sa mounted (cf. pivot supports ps) to be cockedback pivotingly to a disabled position (e.g. as shown in full for s-a from a static position (s-a in phantom) by an associated eccentrically rotating cam means cc-1 (static position in phantom). Here, each slug is cut-out (e.g. cut-out ga-l) so as to clear the actuation stroke of the associated actuator (e.g. AH when so disbaled. Conversely, it will be understood that when such a slug is not disabled, its actuator will print-drive it. Here, as before, only one slug in each actuator-sharing group (others not shown) will be enabled (not disabled) at any one period in each cycle.

Conversely, the cam-thrusting means (e.g. fingers ft, FIGURE 5) may, themselves, absorb the drive-energy imparted to non-selected slugs (e.g. ft comprise flexure springs, etc.). It will also be recognized that the taught (disabling) slug-select features in the foregoing may within the skill of the art analogously enable a selected slug (in a common-actuator group) such as by cocking it toward its actuator (the other slug maintaining a normal position from which it cannot be sufficiently thrust to reach the print plane) and damping means (e.g. springs) provided to control the thrust-excursions. Similarly, a single select means may be shared among a group of slugs (e.g. to operate several simultaneously, such as enabling a first pair, then a second pair; while other means such as staggered font providing selection between pairs so operated).

The foregoing, and similar, select techniques may also be combined in some instances, being combined with one another or with other select techniques (e.g. with such known approaches as are taught in US. 3,220,343, US. 3,332,343 or the like). For instance (and only to illustrate the point but not to indicate a combination which is necessarily desirable) offset means like that in FIGURE 4 might be combined with stop means like that in FIG- URE 5; such as by arranging groups of four slugs (S S S S to share common actuators, while letting a first bar SB (FIGURE 4) shuttle to alternately disable both S S then both S 8,; the while shuttling a second, incorporated bar SB (FIGURE 5) to alternately stop S +S then S +S each bar sharing such shuttling by alternating their disabling shifts. Such a combination could advantageously reduce the required frequency of bar-shifting. Those skilled in the art will appreciate that the taught features may likewise be otherwise combined, with one another, or with other relevant prior art arrangements (such as type rolls with staggered font, shuttling rolls, shuttling paper, shuttling hammers, etc.). They will also appreciate that these features may be applied to other analogous apparatus such as chain printers, train printers, or the like.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. A printing hammer arrangement for a line printer comprising,

movable type carrier means for successively placing type in a printing zone,

a plurality of type impact means supported along respective column portions of said zone for selectively impacting said type, each said impact means including a slug and support means normally mounting said slug in an enabled state adjacent said printing zone for free flight launching,

coupling means synchronously connected to each of said impact means for periodically changing its respective slug to a disabled state, and

actuating means supported adjacent said impact means for selectively contacting said impact means in response to print command signals to launch those slugs in an enabled state into impacting relationship with said type, each said actuating means being operatively connected to a plurality of impact means for selectively launching the slugs of said plurality of impact means upon command during a time shared cycle.

2. A hammer arrangement as described in claim 1 wherein said coupling means comprises stop means for periodically engaging predetermined ones of said slugs to limit the excursion path of said slugs short of an impacting relationship with said type.

3. A hammer arrangement as described in claim 2 wherein said stop means comprise resilient rubber pads located upon a shutting bar disposed in spaced alignment with said slugs, one pad being provided for a predetermined plurality of slugs, each said pad being relieved at a prescribed section, and further including means for laterally reciprocating said bar wherey ditferent ones of said plurality of slugs are enabled at different periods during an operating cycle.

4. A hammer arrangement as described in claim 1 wherein each of said slugs includes a cam follower surface and said coupling means comprises cam means engaging the cam follower surfaces of said respective slugs for periodically moving said slugs to a disabled position.

5. A hammer arrangement as described in claim 4 wherein each of said slugs further includes an impact face, the impact faces of said respective slugs being normally aligned in an enabled position along a plane adjacent said printing zone, and further including moving means for commonly shifting all said cam means to synchronously disable prescribed ones of said plurality of slugs.

6. A hammer arrangement as described in claim 5 wherein said cam means comprises a shuttling cockingbar disposed in spaced alignment with said cam follower surfaces, having notches formed therein at prescribed locations with respect to said column positions and said moving means comprises means for laterally reciprocating said bar.

7. A hammer arrangement as described in claim 5 wherein said moving means comprises a rotatable shaft disposed in spaced alignment with respect to said calm follower surfaces and said cam means comprise sets of cam lobes supported symmetrically about the periphery 12 of said shaft, each of said lobes being disposed within a groove of a corresponding slug to periodically move said slug toward said print zone into said disabled position. 8. A hammer arrangement as described in claim 7 wherein adjacent pairs of lobes are opposed on said shaft for alternately disabling their corresponding slugs, said actuating means including a separate hamvmer face spanning the slugs associated with each said pair of lobes and wherein said type carrier means presents a set of type adjacent each slug, said type being arranged in staggered sets on said carrier means to synchronously register with said enabled slugs during an operating cycle.

References Cited UNITED STATES PATENTS Re. 26,240 7/1967 Wasserman 101-93 2,766,686 10/1956 Fomenko et al. 101-93 2,893,313 7/1959 Pekar et a1 101-93 3,128,694 4/1964 Kittler 101-93 3,247,788 4/1966 Wilkins et a1. 101-93 3,332,343 7/1967 Sims 10193 3,342,127 9/1967 Pitt 10193 OTHER REFERENCES IBM Technical Disclosure Bulletin, vol. 9, No. 8, January 1967, pp. 1013-1014.

ILLIAM B. PENN, Primary Examiner 

